Structure and expression of the parotid secretory protein gene of mouse

Area of Science:

• Molecular Biology
• Genomics
• Gene Expression Analysis

Background:

• Parotid secretory protein (PSP) is the most abundant gene product in the mouse parotid gland, with mRNA accumulating to approximately 5 X 10(4) molecules per cell.
• Analysis of 11 mouse tissues confirmed exclusive expression of the PSP gene in the parotid gland.

Purpose of the Study:

• To clone and characterize the mouse parotid secretory protein (PSP) gene.
• To determine the structure and regulatory elements of the PSP transcription unit.

Main Methods:

• Cloning of a 27,000 base DNA segment containing the PSP transcription unit.
• S1 nuclease method to determine intron-exon structure.
• Nascent parotid transcript hybridization to localize transcription termination.
• Primer extension sequencing to determine transcription initiation site.

Main Results:

• The PSP gene is the sole gene within the cloned DNA segment efficiently expressed in the parotid gland.
• The PSP gene comprises eight introns and nine exons, spanning 8300 bases from the cap nucleotide to the poly(A) addition site.
• Transcription termination was localized to a 700 base-pair region downstream from the poly(A) site.
• Genomic DNA upstream of the initiation site contains TATA and CAAT motifs, along with enhancer-like sequences.

Conclusions:

• The study provides a comprehensive characterization of the mouse parotid secretory protein (PSP) gene.
• Identified regulatory elements suggest complex transcriptional control of PSP expression in the parotid gland.